<template>
  <div class="slide-verify" :style="{width: w + 'px'}" id="slideVerify" onselectstart="return false;">
    <!-- 图片加载遮蔽罩 -->
    <div :class="{'slider-verify-loading': loadBlock}"></div>
    <canvas :width="w" :height="h" ref="canvas" ></canvas>
    <div v-if="show" @click="refresh" class="slide-verify-refresh-icon"></div>
    <canvas :width="w" :height="h" ref="block"  class="slide-verify-block"></canvas>
    <!-- container -->
    <div class="slide-verify-slider" :class="{'container-active': containerActive, 'container-success': containerSuccess, 'container-fail': containerFail}">
      <div class="slide-verify-slider-mask" :style="{width: sliderMaskWidth}">
        <!-- slider -->
        <div @mousedown="sliderDown"
             @touchstart="touchStartEvent"
             @touchmove="touchMoveEvent"
             @touchend="touchEndEvent"
             class="slide-verify-slider-mask-item"
             :style="{left: sliderLeft}">
          <div class="slide-verify-slider-mask-item-icon"></div>
        </div>
      </div>
      <span class="slide-verify-slider-text">{{sliderText}}</span>
    </div>
  </div>
</template>
<script>
  const PI = Math.PI;

  function sum(x, y) {
    return x + y
  }

  function square(x) {
    return x * x
  }
  export default {
    name: 'SlideVerify',
    props: {
      // block length
      l: {
        type: Number,
        default: 42,
      },
      // block radius
      r: {
        type: Number,
        default: 10,
      },
      // canvas width
      w: {
        type: Number,
        default: 310,
      },
      // canvas height
      h: {
        type: Number,
        default: 155,
      },
      sliderText: {
        type: String,
        default: 'Slide filled right',
      },
      accuracy: {
        type: Number,
        default: 5, // 若为 -1 则不进行机器判断
      },
      show: {
        type: Boolean,
        default: true,
      },
      imgs: {
        type: Array,
        default: () => [],
      },
    },
    data() {
      return {
        containerActive: false, // container active class
        containerSuccess: false, // container success class
        containerFail: false, // container fail class
        canvasCtx: null,
        blockCtx: null,
        block: null,
        block_x: undefined, // container random position
        block_y: undefined,
        L: this.l + this.r * 2 + 3, // block real lenght
        img: undefined,
        originX: undefined,
        originY: undefined,
        isMouseDown: false,
        trail: [],
        sliderLeft: 0, // block right offset
        sliderMaskWidth: 0, // mask width,
        success: false, // Bug Fixes 修复了验证成功后还能滑动
        loadBlock: true, // Features 图片加载提示，防止图片没加载完就开始验证
        timestamp: null,
      }
    },
    mounted() {
      this.init()
    },
    methods: {
      init() {
        this.initDom()
        this.initImg()
        this.bindEvents()
      },
      initDom() {
        this.block = this.$refs.block;
        this.canvasCtx = this.$refs.canvas.getContext('2d')
        this.blockCtx = this.block.getContext('2d')
      },
      initImg() {
        const img = this.createImg(() => {
          // 图片加载完关闭遮蔽罩
          this.loadBlock = false;
          this.drawBlock()
          this.canvasCtx.drawImage(img, 0, 0, this.w, this.h)
          this.blockCtx.drawImage(img, 0, 0, this.w, this.h)
          let {
            block_x: x,
            block_y: y,
            r,
            L
          } = this
          let _y = y - r * 2 - 1
          let ImageData = this.blockCtx.getImageData(x, _y, L, L);
          this.block.width = L;
          this.blockCtx.putImageData(ImageData, 0, _y)
        });
        this.img = img;
      },
      drawBlock() {
        this.block_x = this.getRandomNumberByRange(this.L + 10, this.w - (this.L + 10))
        this.block_y = this.getRandomNumberByRange(10 + this.r * 2, this.h - (this.L + 10))
        this.draw(this.canvasCtx, this.block_x, this.block_y, 'fill')
        this.draw(this.blockCtx, this.block_x, this.block_y, 'clip')
      },
      draw(ctx, x, y, operation) {
        let {
          l,
          r
        } = this;
        ctx.beginPath()
        ctx.moveTo(x, y)
        ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
        ctx.lineTo(x + l, y)
        ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
        ctx.lineTo(x + l, y + l)
        ctx.lineTo(x, y + l)
        ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
        ctx.lineTo(x, y)
        ctx.lineWidth = 2
        ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
        ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
        ctx.stroke()
        ctx[operation]()
        // Bug Fixes 修复了火狐和ie显示问题
        ctx.globalCompositeOperation = "destination-over"
      },
      createImg(onload) {
        const img = document.createElement('img');
        img.crossOrigin = "Anonymous";
        img.onload = onload;
        img.onerror = () => {
          img.src = this.getRandomImg()
        }
        img.src = this.getRandomImg()
        return img;
      },
      // 随机生成img src
      getRandomImg() {
        // return require('../assets/img.jpg')
        const len = this.imgs.length;
        return len > 0 ?
          this.imgs[this.getRandomNumberByRange(0, len)] :
          'https://picsum.photos/300/150/?image=' + this.getRandomNumberByRange(0, 1084);
      },
      getRandomNumberByRange(start, end) {
        return Math.round(Math.random() * (end - start) + start)
      },
      refresh() {
        this.loadBlock = true
        this.reset()
        this.$emit('refresh')
      },
      sliderDown(event) {
        if (this.success) return;
        this.originX = event.clientX;
        this.originY = event.clientY;
        this.isMouseDown = true;
        this.timestamp = + new Date();
      },
      touchStartEvent(e) {
        if (this.success) return;
        this.originX = e.changedTouches[0].pageX;
        this.originY = e.changedTouches[0].pageY;
        this.isMouseDown = true;
        this.timestamp = + new Date();
      },
      bindEvents() {
        document.addEventListener('mousemove', (e) => {
          if (!this.isMouseDown) return false;
          const moveX = e.clientX - this.originX;
          const moveY = e.clientY - this.originY;
          if (moveX < 0 || moveX + 38 >= this.w) return false;
          this.sliderLeft = moveX + 'px';
          let blockLeft = (this.w - 40 - 20) / (this.w - 40) * moveX;
          this.block.style.left = blockLeft + 'px';

          this.containerActive = true; // add active
          this.sliderMaskWidth = moveX + 'px';
          this.trail.push(moveY);
        });
        document.addEventListener('mouseup', (e) => {
          if (!this.isMouseDown) return false
          this.isMouseDown = false
          if (e.clientX === this.originX) return false;
          this.containerActive = false; // remove active
          this.timestamp = + new Date() - this.timestamp;

          const {
            spliced,
            TuringTest
          } = this.verify();
          if (spliced) {
            if(this.accuracy === -1) {
              this.containerSuccess = true;
              this.success = true;
              this.$emit('success', this.timestamp);
              return;
            }
            if (TuringTest) {
              // succ
              this.containerSuccess = true;
              this.success = true;
              this.$emit('success', this.timestamp)
            } else {
              this.containerFail = true;
              this.$emit('again')
            }
          } else {
            this.containerFail = true;
            this.$emit('fail')
            setTimeout(() => {
              this.reset()
            }, 1000)
          }
        })
      },
      touchMoveEvent(e) {
        if (!this.isMouseDown) return false;
        const moveX = e.changedTouches[0].pageX - this.originX;
        const moveY = e.changedTouches[0].pageY - this.originY;
        if (moveX < 0 || moveX + 38 >= this.w) return false;
        this.sliderLeft = moveX + 'px';
        let blockLeft = (this.w - 40 - 20) / (this.w - 40) * moveX;
        this.block.style.left = blockLeft + 'px';

        this.containerActive = true;
        this.sliderMaskWidth = moveX + 'px';
        this.trail.push(moveY);
      },
      touchEndEvent(e) {
        if (!this.isMouseDown) return false
        this.isMouseDown = false
        if (e.changedTouches[0].pageX === this.originX) return false;
        this.containerActive = false;
        this.timestamp = + new Date() - this.timestamp;

        const {
          spliced,
          TuringTest
        } = this.verify();
        if (spliced) {
          if(this.accuracy === -1) {
            this.containerSuccess = true;
            this.success = true;
            this.$emit('success', this.timestamp);
            return;
          }
          if (TuringTest) {
            // succ
            this.containerSuccess = true;
            this.success = true;
            this.$emit('success', this.timestamp)
          } else {
            this.containerFail = true;
            this.$emit('again')
          }
        } else {
          this.containerFail = true;
          this.$emit('fail')
          setTimeout(() => {
            this.reset()
          }, 1000)
        }
      },
      verify() {
        const arr = this.trail // drag y move distance
        const average = arr.reduce(sum) / arr.length // average
        const deviations = arr.map(x => x - average) // deviation array
        const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length) // standard deviation
        const left = parseInt(this.block.style.left)
        const accuracy = this.accuracy <= 1 ? 1 : this.accuracy > 10 ? 10 : this.accuracy;
        return {
          spliced: Math.abs(left - this.block_x) <= accuracy,
          TuringTest: average !== stddev, // equal => not person operate
        }
      },
      reset() {
        this.containerFail = false
        this.success = false;
        this.containerActive = false;
        this.containerSuccess = false;
        this.containerFail = false;
        this.sliderLeft = 0;
        this.block.style.left = 0;
        this.sliderMaskWidth = 0;
        // canvas
        let {
          w,
          h
        } = this;
        this.canvasCtx.clearRect(0, 0, w, h)
        this.blockCtx.clearRect(0, 0, w, h)
        this.block.width = w

        // generate img
        this.img.src = this.getRandomImg();
        this.$emit('fulfilled')
      },
    }
  }
</script>
<style scoped>
  .slide-verify {
    position: relative;
  }

  /* 图片加载样式 */
  .slider-verify-loading{
    position: absolute;
    top: 0;
    right: 0;
    left: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    z-index: 999;
    animation: loading 1.5s infinite;
  }

  @keyframes loading {
    0%{
      opacity: .7;
    }
    100% {
      opacity: 9;
    }
  }

  .slide-verify-block {
    position: absolute;
    left: 0;
    top: 0
  }

  .slide-verify-refresh-icon {
    position: absolute;
    right: 0;
    top: 0;
    width: 34px;
    height: 34px;
    cursor: pointer;
    background: url("../../assets/slide_verify/icon_light.png") 0 -437px;
    background-size: 34px 471px
  }

  .slide-verify-slider {
    position: relative;
    text-align: center;
    width: 100%;
    height: 40px;
    line-height: 40px;
    margin-top: 15px;
    background: #f7f9fa;
    color: #45494c;
    border: 1px solid #e4e7eb
  }

  .slide-verify-slider-mask {
    position: absolute;
    left: 0;
    top: 0;
    height: 40px;
    border: 0 solid #1991FA;
    background: #D1E9FE
  }

  .slide-verify-slider-mask-item {
    position: absolute;
    top: 0;
    left: 0;
    width: 40px;
    height: 40px;
    background: #fff;
    box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
    cursor: pointer;
    transition: background .2s linear
  }

  .slide-verify-slider-mask-item:hover {
    background: #1991FA
  }

  .slide-verify-slider-mask-item:hover .slide-verify-slider-mask-item-icon {
    background-position: 0 -13px
  }

  .slide-verify-slider-mask-item-icon {
    position: absolute;
    top: 15px;
    left: 13px;
    width: 14px;
    height: 12px;
    background: url("../../assets/slide_verify/icon_light.png") 0 -26px;
    background-size: 34px 471px
  }
  .container-active .slide-verify-slider-mask-item {
    height: 38px;
    top: -1px;
    border: 1px solid #1991FA;
  }

  .container-active .slide-verify-slider-mask {
    height: 38px;
    border-width: 1px;
  }

  .container-success .slide-verify-slider-mask-item {
    height: 38px;
    top: -1px;
    border: 1px solid #52CCBA;
    background-color: #52CCBA !important;
  }

  .container-success .slide-verify-slider-mask {
    height: 38px;
    border: 1px solid #52CCBA;
    background-color: #D2F4EF;
  }

  .container-success .slide-verify-slider-mask-item-icon {
    background-position: 0 0 !important;
  }

  .container-fail .slide-verify-slider-mask-item {
    height: 38px;
    top: -1px;
    border: 1px solid #f57a7a;
    background-color: #f57a7a !important;
  }

  .container-fail .slide-verify-slider-mask {
    height: 38px;
    border: 1px solid #f57a7a;
    background-color: #fce1e1;
  }

  .container-fail .slide-verify-slider-mask-item-icon {
    top: 14px;
    background-position: 0 -82px !important;
  }

  .container-active .slide-verify-slider-text,
  .container-success .slide-verify-slider-text,
  .container-fail .slide-verify-slider-text {
    display: none;
  }
</style>
